Embodiments of the present disclosure generally relate to an energy exchange assembly, such as an energy recovery core, and, more particularly, to a system and method of forming an energy exchange assembly.
Energy exchange assemblies are used to transfer energy, such as sensible and/or latent energy, between fluid streams. For example, air-to-air energy recovery cores are used in heating, ventilation, and air conditioning (HVAC) applications to transfer heat (sensible energy) and moisture (latent energy) between two airstreams. A typical energy recovery core is configured to precondition outdoor air to a desired condition through the use of air that is exhausted out of the building. For example, outside or supply air is channeled through the energy recovery core in proximity to exhaust air. Energy between the supply and exhaust air streams is transferred therebetween. In the winter, for example, cool and dry outside air is warmed and humidified through energy transfer with the warm and moist exhaust air. As such, the sensible and latent energy of the outside air is increased, while the sensible and latent energy of the exhaust air is decreased. The energy recovery core typically reduces post-conditioning of the supply air before it enters the building, thereby reducing overall energy use of the system.
Air-to-air recovery cores may include a membrane through which heat and moisture are transferred between air streams. The membrane may be separated from adjacent membranes using a spacer. In an energy recovery core, the amount of heat transferred is generally determined by a temperature difference and convective heat transfer coefficient of the two air streams, as well as the material properties of the membrane. The amount of moisture transferred in the core is generally governed by a humidity difference and convective mass transfer coefficients of the two air streams, but also depends on the material properties of the membrane.
The design and assembly of the energy recovery core may also affect the heat and moisture transfer between air streams, which impacts the performance and cost of the energy core. For example, if the membrane does not properly adhere to the spacer, an increase in air leakage and pressure drop may occur, thereby decreasing the performance (measured as latent effectiveness) of the energy recovery core. Conversely, if excessive adhesive is used to secure the membrane to the spacer, the area available for heat and moisture transfer may be reduced, thereby limiting or otherwise reducing the performance of the energy recovery core. Moreover, the use of adhesives in relation to the membrane also adds additional cost and labor during assembly of the core.
A known method of assembling an energy recovery core includes gluing a membrane to an air spacer and then stacking layers of membrane and spacer to a desired height. As one example, the membrane may be cut into sheets the same size as the air spacer, then glued to the air spacer with dots of glue along peaks of a sinusoidal-shaped body of the air spacer. When the membrane is pressed onto the air spacer the glue spreads out along the membrane surface, thereby reducing the area of membrane that is available for energy transfer. In another example, the membrane is cut into sheets the same width as the air spacer, but longer in the length-wise direction than the air spacer. The sheets are then wrapped around the edge of the spacer and glued into place. The area of the membrane where the glue is applied is then blocked off, thereby preventing moisture transfer.
Another known method of assembling an energy recovery core includes using two rolls of membrane material. Each membrane roll has a width that is half a diagonal length of an air spacer. Each membrane roll is wrapped around the air spacer in opposite directions. The rolls are then wrapped diagonally around the air spacer and the process is continued until the stack has reached a desired height. During this process, a seam is created down the middle of each layer, which is then taped at the seam. However, the tape reduces the area of membrane available for heat and moisture transfer.